Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Computing systems include an increased number of shared system resources, such as memory, buses, and communication interfaces. Additionally, an increased number of entities (e.g., users and clients) are sharing those resources. These different entities have different requirements on using the shared resource in the computer system. For example, some entities, like a computer processing unit (CPU), care about the access latency when fetching an instruction; and other entities, such as direct memory access (DMA) controllers, care most about throughput. An arbiter is used to manage the use of the shared resources efficiently and to best meet the requirements of different entities in the computing system.
Different arbitration algorithms, such as round robin, weighted round robin, least recently used (LRU), and most recently used (MRU), have been developed to improve the performance and fairness of the arbitration to meet different system requirements. However, as the system speed runs faster and faster, and there are more and more entities included in the arbitration, the arbiter may have trouble meeting the system design requirements. For example, if there are 64 clients that share one resource, there are 64 bits of requests. The typical arbitration cycle is fixed, such as each arbitration is performed in one clock cycle. However, when a high clock speed is used, it is difficult to achieve one cycle arbitration with even a simple round robin algorithm.